How to block SSL Labs
Operated by Qualys. is Qualys' free online SSL/TLS security testing service that performs deep analysis of SSL web server configurations on the public Internet to identify security … Security Scanner Scans websites for security vulnerabilities, threats, and configuration weaknesses
How it identifies itself
TLS tester from https://testssl.sh/
nginx
In the server block, then reload.
# In the server block. 403 rather than 444: a closed connection tells the
# operator nothing, and an agent that gets a status code can log it.
if ($http_user_agent ~* "(SSL Labs)") {
return 403;
}
Apache
In .htaccess or the vhost.
BrowserMatchNoCase "SSL Labs" bad_bot
<RequireAll>
Require all granted
Require not env bad_bot
</RequireAll>
Cloudflare
Security → WAF → Custom rules.
# Security → WAF → Custom rules, action: Block (http.user_agent contains "SSL Labs")
WordPress
A child theme's functions.php, or a small plugin.
// functions.php of a child theme, or a small plugin. Runs before WordPress
// builds the page, so a blocked agent costs one PHP process and no queries.
add_action('init', function () {
$agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
foreach (['SSL Labs'] as $needle) {
if (stripos($agent, $needle) !== false) {
status_header(403);
exit('Blocked: SSL Labs');
}
}
});
A rule on the user agent is a rule on a string it chose
The server rules match on a header the requester sets, which stops the agent that says who it is and not the one that copies somebody else's name. Botscope verifies identity against DNS and published address ranges, records which check decided each request, and shows you the ones that lied.